Process for rendering cellulosecontaining material crease-resistant and products obtained thereby



Patented June is, 1940 UNITED STATES raocass ron PATENT OFFICE RENDERING'CELLULOSE- I CONTAINING MATERIAL GREASE-RESIST- ANT AND PRODUCTSOBTAINEDTHEREBY George Heberlein, .Ir., Ernst Weiss, and Hans Hemmi,Wattwil, Switzerland. assignors Heberlein Patent Corporation, New York,N. Y., a corporation of New York No Drawing. Application December 23.1937, Se-

riai No. 181,454. In Germany December 28,

cotton and other natural cellulose-containing fibers, as well asregenerated cellulose, artificial silk fibers such for example asviscose and cuprammonium can be produced without deposition of anartificial resin within or on the fiber by treatment with formalydehydeand a suitable catalyst. According to this prior process fabrics, yarnsand unspun fibers of materialsmentioned above were preferably steeped inan aqueous solution of formaldehyde of proper strength which contained acatalyst of a non-alkaline character, and, if necessary, werecentrifuged or rung out and thereupon heated while substantially dry toa temperature of about -160" '0. The materials treated according to thisprocess not only were wrinkle-proof but showed an almost completefreedom from shrinkage. prior process resultedin'some decrease of thestrength of the materials treated.

We have found in accordance with the present invention thatcellulose-containing material can be made crease-resistant and itsstrength substantially maintained by treating it with a swelling agentand thereafter with formaldehyde in the presence of a non-alkalinecatalyst, and heating while dry to a temperature of about 90 C. to aboutC. for a suiiicient length of time to produce an effectivewrinkle-resistance: During the treatment with the swelling agent we havealso found that'further improvement in the strength and other valuableproperties may be given to natural cellulose fiber, for example such ascotton, by giving it a caustic swellingand shrinking 'andthen,stretching it preferably beyond its original" length, andthereafter proceeding with the wrinkle-resistant treatment. We

have also found that improved effect yarns may- This a particularlycaustic soda solution.

11 Claims. (01. 8-416) accordance with which we now prefer to practicethe invention. 4

' We havefound that the invention can be carried out in a simple andeffective manner by exposing the goods before the wrinkle-resistanttreatment to the action of a swelling agent, leaving the goods a shorttime in such condition, then thoroughly washing out the swelling agentand then treating them, in the manner above referred to, withformaldehyde in the presence of a nonalkaline catalyst and heating themfor a sumcient length of time to about 90 C. to about 160 C. to producethe desired crease-resistance. The surprising fact has been notedaccordingly in so carrying out our process that-it is not only possibleto improve the strength of the goods but in addition to this if thegoods so treated by prethe same time the tensile strength may beincreased beyond the tenslle strengthof the un-- treated material. Thebreaking elongation and tensile strength of cotton is-also improved bythe process. Resistance to swelling agents for example is shown by thefollowing: If parchmentizing sulfuric acid is allowed to act on thegoods for more than one minute or mercerizing lye (caustic soda) isallowed to act for several hours, no shrinking or other change isnoticeable. We have also found that material treated in accord- "ancewiththe invention is almost completely immune to substantive dyestuffs.

' All of the known swelling agents may be employed for the carrying outof preliminary treatment in accordance with our invention. For'instancealkalis, such as caustic soda solution, ca'us tic potash solution,quaternary ammonium bases, various acids, such as sulfuric acid,phosphoric acid, etc. may be employed. Salt solutions, such as calciumrhodanide, zinc chloride, ammoniacal copper oxide and others may beused. However,

caustic alkalis appear to be especially suitable, These excel because oftheir low price and particularly because of good results which they givein in creasing the breaking elongation, tensile strength and resistanceto swelling agents ofxthe com pletcd material.

In treating various textile 50 materials there must be taken intoconsideration in each indi-.--

able efi'ect can be observed at a strength of 2 B. while for goodresults concentrations of 6 B. or more are required. Concentrations ofup to even higher than 30 B. can be applied, if desired. Caustic sodasolution may also be used provided concentrations are employed whichwill not cause injury to the rayon. Good results can be obtained with acaustic soda lye of about 3 B. but higher'concentrations may be appliedif desired. It is advisable to subject the rayon for a number of minutesin untensioned condition to the action of the swelling agent, then towash thoroughly, if necessary, with hot water and to follow this, with,or without intermediate dyeing, by the formaldehyde treatment. Normallythe swelling agent is used atroom temperature, but higher and lowertemperatures may also be used.

In the case of cotton goods results may be obtained with concentrationsof the swelling agents which are higher than the lower limits which canbe used for rayon. If one uses lye of mercerizing strength, one obtainsan improved breaking elongation with moderate tensile strength if thegoods are treated in loose condition and are allowed to shrink in thelye. A particularly good tensile strength is obtained if the goods,preferably in the form of yarn, are first caused to shrink under theaction of the lye, to their minimum length, and thereupon are stretched.It has been found that the effect thus obtained is better than thatproduced by standard mercerizing treatment in which the yarn is keptuniformly under tension from the beginning of the treatment to the end.

In general in the case of cotton the tensile strength is greater, themore strongly the yarn impregnated with the swelling agent is thereafterstretched after complete shrinking. Stretchings even beyond the originallength can be applied complete wetting through with the swelling agentand subsequently with formaldehyde where the latter is employed insolution. n the other hand it is not necessary to bleach the fibersbefore the treatment in accordance with the invention for the purpose ofdestroying the natural colors contained therein by meansof hypochlorite,peroxide of hydrogen, etc., although such bleaching may be practised, ifdesired.

The resistance to swelling agents referred to above is'of specialimportance if the process 'of the invention is applied to'yams and theseyarns are thereupon woven as effects in a. fabric otherwise consistingof untreated fiber material. The finished fabric, which for instance mayconsist on the one hand of raw cotton yarn and on the other hand ofcotton yarn or rayon yarn treated in accordance with our invention aseffect yarns, can be scoured (kier boiled) andbleached withoutdifliculty and without losing the valuable realone or in combinationwith other fibers.

parchmentizing action or other known swelling agents, the effect yarnsremain unchanged while the other yarns in the manner known per se anddepending on the kind of finishing liquor or bath,

. shrink, become stiff, transparent or the like. As

further fibrous materials suitable for treatment by the swelling agentfor preparing such fabrics in which the effect yarns are woven, we mayemploy other cellulose containing yarns such as rayon, linen, cell wool(viscose spun rayon) or the like, and also animal fibers.

The following are specific examples of the process as we now prefer topractice it. It is to be understood that these examples are simplyillustrative and that the invention is not limited thereto except asindicated in the appended claims.

Examples 1. Cotton yarn in skeins is normally mercerised with causticsoda of 32 B. in a yarn mercerizing apparatus. It is then washed outwith hot and cold water and dried. Thereupon the yarn is impregnated ina bath containing 56 liters of water, 40 liters of formaldehyde 40% and40 liters of solution of aluminium sulphocyanide of 17 B. It is thencentrifuged and dried during several hours at 50-60 C. After this it isheated during a quarter of an hour at 120-125 C. and finally, toeliminate the odour of formaldehyde, washed out with a diluted solutionof soap or ammonia in water, rinsed and dried- 2. Cotton yarn, the sameas above, are treated following Example 1 with the exception thatinstead of normally mercerizing it is stretched just beneath thetearing-limit during the mercerisation. a

The tensile strength of the overstretched mercerized yarn is about 20%higher than the tensile strength of the normally mercerized yarn and isof the same range or beyond the range of the unmercerized untreatedpreliminary material. The material so treated shows a higher orientationin its micelles.

3. Viscose-yarn is desized with a solution of 3 g. soap per liter andone of the usual textile assistants and then first washed with warm andsubsequently with cold water and dried. Thereupon it is swelled in aloose condition with caustic potash of 6 B. during minutes at 18-20 C.,rinsed with boiling water, washed out with cold water and soured withsulphuric acid of 08 B., washed and. dried. The yarn is then treatedwith the same impregnating bath as described above in Example 1 during10 minutes, centrifuged and dried during several hours.' After this itis heated during minutes at 118-120" C. 'For deodorization it may thenbe rinsed with a diluted soap or ammonia-solution, washed out and dried.

The breaking elongation of the so-treated viscose-yam is about higherthan the breaking elongation of a formaldehyde-treated yarn which hadnot been swelled before, whereas the tensile strength is about of thesame range or beyond the tensile strength of the untreated preliminarymaterial.

In the aplpended claims where the expression cellulose-c ntainingmaterial" or cellulose-containing fabric or the like expressions areused, they are employed to cover cotton'or other naturalcellulose-containing fibers, as well as allregenerated-cellulose-artificial silks for example such as viscose andcuprammoniui'n silk; and in th form of flbersg-yarn or fabric, eitherused In the process claims where the expression formaldehyde is used, itis intended to include polymers of formaldehyde andformaldehyde-splitting compounds. Where the expression nonalkalinecatalyst is used it is employed to cover acid catalysts, substancesliberating an acid catalyst in solution or when exposed to the reactionconditions here described in which latter case they may also be neutralin the original state, but not alkaline catalysts. v

While the invention has been described in detail with respect toparticular preferred examples, it will be understood by those skilled inthe art after understanding the invention that various changes andfurther modifications may be made without departing from the spirit andscope of the invention and it is intended therefore in the appendedclaims to cover all such changes and I modifications.

What'is claimed as new and desired to be secured by Letters Patent, is:

1. A process for rendering cellulose-containing materialcrease-resistant which comprises treating cellulose-containing materialwith a swelling agent, thereafter impregnating the material withformaldehyde in the presence of a non-alkaline catalyst, heating theimpregnated material while substantially dry for a sufficient length oftime to about 90-160 C. and causing a chemical combinationbetween thecellulose and formaldehyde whereby an effective crease-resistant qualityis obtained and the tendency of the formaldehyde to weaken the fiber isat least in part offset by the preswelling.

2. A process for rendering cellulose-containing materialcrease-resistant which comprises treating cotton with caustic alkali ofmercerizing strength, thereafter impregnating the material withformaldehyde in the presence of a nonalkaline catalyst, heating theimpregnated ma terial while substantially dry for a suiflcient.

length of time to about 90-160 C. and causing a chemical combinationbetween the cellulose and swelling agent is applied at a temperature of.the.

order of 50-100 C.

4. A process according to claim 2 in which the mercerizing agent is atapproximately 50 C. or above and the mercerizing liquor is ofapproximately 30 36.

5. A process for rendering cellulose-containing materialcrease-resistant which comprises treating artificial silk with causticpotash of swelling strength, thereafter impregnating the material with acrease-resistant agent which consists principally of formaldehyde in thepresence of anonalkaline catalyst and heating the impregnated materialwhile dry for a suflicient length of time to about 90-160 C. whereby aneffective creaseresistant quality. is obtained.

6. A process for renderingcellulose-containing material crease-resistantwhich comprises treat-' ing cotton with a swelling agent, therebyshrinking the cotton, then stretching the cotton,

thereafter impregnating the material with a crease-resistant agent whichconsists principally of formaldehyde in the presence of a non-alkalinecatalyst and heating the impregnated material .while dry for asufllcient length of time to about 90-160 C. whereby an effectivecrease-resistant quality is obtained.

7. A- process according to-claim 6 in which the cotton is first swollenand shrunk with caustic alkali of mercerizing strength and thenstretched so that it has a greater length than it had prior to thetreatmentwith the. caustic alkali.

8. A process for rendering cellulose-containing materialcrease-resistant which comprises subjecting cotton to a mercerizingalkali treatment thereby mercerizing and shrinking it, stretching thecotton to beyond its original length while washing it to remove thealkali, then impregnating the cotton while still in the stretchedcondition with formaldehyde in the presence of a non-alkalinecatalystandheating the impregnated material while dry for a suflicient length oftime to about 90-160 C. thereby giving to the cotton an effectivecrease-resistant quality and improved strength.

9. As a new product, a substantially shrinkproof cellulose-containingmaterial swollen with a swelling agent and thereafter chemicallycombined with formaldehyde, said product'having a strength substantiallyhigher than such material treated with formaldehyde without thepreliminary swelling treatment. p

10. A new product in accordance with claim 9 in which the swelling agentemployed is an alkaline mercerizing agent.

11. A new product in accordance with claim 9 in which thecellulose-containing material is cotton having a high orientation in itsmicelles.

GEORGE Ja. ERNST wares HANS

